1. Field of the Invention
The present invention relates generally to a robotic vision, optical correlation system which utilizes matched filters to provide object identification, and to provide aspect information, such as positional and size information, about an object, and more particularly pertains to a robotic vision system as described which utilizes primarily parallel optical processing therein.
2. Discussion of the Prior Art
The study and application of robotic vision systems is an area that is accelerating in interest in both commercial and military activities. Current commercial applications have been identified for machine operations and production lines. In the prior art, robot manipulators have been utilized in relatively large scale manufacturing assembly lines to perform simple manipulative tasks including loading and unloading machines, stacking parts, spray painting, and spot-welding. These machines generally responded to a set of highly specific program commands wherein the positioning and orientation of the workpieces manipulated were known with considerable precision. In general, the programming of such a manipulator was relatively complicated, and the program was useful only if the positioning of the workpieces was held within relatively precise tolerances.
Recently, there has been an attempt to increase the flexibility of such manipulators by the addition of various sensory capabilities. Tactile and auditory capabilities are presently being developed along with visual capabilities, as concerns the present invention. Range finding, and structured light and binocular vision techniques have been employed in such robotic vision systems. However, none of these systems are particularly useful in applications requiring identification of an object, and a determination of its location and orientation. Furthermore, the known robotic vision systems require a substantial amount of processing time between vision sensing and object identification.
A number of robotic or machine vision systems have been disclosed and analyzed in the prior art relative to their abilities to perform specific intended tasks. These systems have usually been hybrid in nature, with the sensor often being an analog device, and the processing and articulation control frequently being digital in nature. A further bifurcation in this technology is the choice between digital and analog object recognition. Digital systems often rely upon video input and algorithms to sort out objects and parts according to size and aspect. The memory libraries are restricted only by the size of the computer memory. There are fewer optical systems, and most of them rely upon electronic processing to some degree.
Spight U.S. Pat. No. 4,462,046 discloses an optical vision system in which video cameras are used in association with a computer, and in which off-axis views are stored in the processor. The Fast Fourier Transforms (FFT) are video analyzed and processed in the computer. At best, this system is restricted to thirty frames per second.
In contrast to the Spight system, the present invention performs its processing optically and in parallel at near the speed of light. Many views of many different objects can be stored in a single complex matched filter, and these filters can be specifically designed to handle multiple objects. A further advantage of the subject invention is that specially designed multiple holographic lenses allow many objects and/or many views to be optically processed in parallel, and also the degree of aspect of an object can be determined to a desired degree of resolution.
Grumet U.S. Pat. 3,779,492 is of interest to the present invention, and discloses a matched filter optical correlator system similar to the present invention in which a coherent, optical signal processor is used for recognition of specific known targets. Each matched filter record includes a pair of matched filters that separately process the high and low spatial frequencies. The outputs thereof are combined in a logical AND operation and the target is interrogated for fine features as well as for correct size and shape. The optical memory bank of matched filter pairs comprises diffraction patterns of all resolvable views, in both azimuth and elevation, of a target, thus forming a target recognition comb-filter bank. All views of the recognition bank are simultaneously interrogated optically according to the diffraction pattern of the detected object to determine whether the detected object is the desired target as stored in any of the views in the memory bank.
The present invention differs from and improves upon the Grumet system in several important respects. One embodiment of the subject invention provides an inverse Fourier transform lens array for receiving the optical correlation outputs of an array of matched filters, and each optical correlation output is then directed to a separate detector. Grumet instead illustrates a single lens 29 which directs all of the outputs onto a common detector. The present invention also provides a normalizing means for each individual matched filter for producing a normalized output signal therefrom, and Grumet totally fails to appreciate the need for signal normalization. The separate detector advantageously allows each output signal to be amplified separately, which allows each amplifier to be used for separate normalization of that processing channel. Grumet also fails to appreciate that each matched filter has a separate and individual angular response curve, which should be formulated, and can be utilized to determine aspect information about an object of interest.